Mobile communication terminal capable of displaying communication mode

ABSTRACT

In a mobile communication terminal connectable to a first base station using a first communication mode and a second base station using a second communication mode that is different from the first communication mode, a control message coming from an acquired one of the first and second base stations is received. Based on the received control message, the communication mode used in the base station is recognized, and information indicative of the recognized communication mode is informed to the user.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/323,838, filed Dec. 20, 2002, which is based upon and claims thebenefit of priority from the prior Japanese Patent Application No.2001-388281, filed Dec. 20, 2001, the entire contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a mobile communication terminal capableof being connected to a plurality of kinds of base stations that usedifferent communication modes.

2. Description of the Related Art

In general, a mobile communication system includes a plurality of basestations which are distributed over the service area. A mobilecommunication terminal selects one of the base stations, which has thebest condition for communication and acquires the selected base station.Thereby, radio communication is enabled.

In the mobile communication system, there may be a case where a part ofthe standards of the communication mode is upgraded while the system isbeing in operation. For example, in mobile communication systems usingCDMA (Code Division Multiple Access), a preparation is now progressingto upgrade IS95A/IS95B standards to IS2000-1X standards designed toincrease a data communication speed, while basic portions of theIS95A/IS95B standards remain unchanged.

It is not possible, however, to upgrade the standards of thecommunication mode for all the base stations of the system at the sametime. In general, the standards are upgraded step by step. Consequently,base stations with different standards are mixedly present in theservice area until completion of the work for upgrading the standardsfor all base stations.

If a mobile communication terminal corresponding to both old and newstandards is to start information communication in this state, it isuncertain whether the terminal is connected to a base station with newstandards or a base station with old standards, depending on theconditions for communication, such as the current location of theterminal or the condition of radio waves. For example, if the mobilecommunication terminal of a use who wishes high-speed data communicationis connected to a base station with old standards, a longer time thanexpected may be consumed until completion of data communication, or ahigh communication charge may occur. This is very disadvantageous.

BRIEF SUMMARY OF THE INVENTION

The object of the present invention is to provide a mobile communicationterminal that enables a user to confirm in advance a usablecommunication mode at the time of starting information communication,thereby preventing undesired information communication from beingperformed.

According to an aspect of the present invention, there is provided amobile communication terminal connectable to a first base station usinga first communication mode and a second base station using a secondcommunication mode that is partly upgraded from the first communicationmode. The terminal includes acquisition means for acquiring one of thefirst and second base stations and indication means for indicating thecommunication mode. The communication mode used in the base station isrecognized from a control message coming from the base station acquiredby the acquisition means. Information representative of the recognizedcommunication mode is informed to the user of the mobile communicationterminal.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate presently preferred embodiments ofthe invention, and together with the general description given above andthe detailed description of the preferred embodiments given below, serveto explain the principles of the invention.

FIG. 1 schematically shows the structure of a mobile communicationsystem according to an embodiment of the present invention;

FIG. 2 is a block diagram showing the structure of a mobilecommunication terminal according to an embodiment of the invention;

FIG. 3 shows a control sequence illustrating the procedures and contentsof a communication mode display control which is performed in the mobilecommunication terminal shown in FIG. 2, when power is turned on or whenan idle handoff is executed in a standby state;

FIG. 4 shows an example of a format of system parameter messages used inthe communication mode display control shown in FIG. 3;

FIG. 5 shows control sequences illustrating the procedures and contentsof a communication mode display control which is performed in the mobilecommunication terminal shown in FIG. 2, when a handoff is executedduring information communication;

FIG. 6 shows an example of a format of handoff direction messages usedin the communication mode display control illustrated in FIG. 5;

FIG. 7 shows an example of a first display image of a communication modeaccording to the communication mode display control shown in FIGS. 3 and5; and

FIG. 8 shows an example of a second display image of a communicationmode according to the communication mode display control shown in FIGS.3 and 5.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of a mobile communication terminal according to thepresent invention will now be described with reference to theaccompanying drawings.

FIG. 1 schematically shows the structure of a mobile communicationsystem adopting a CDMA (Code Division Multiple Access) method accordingto an embodiment of the invention.

A plurality of base stations BS1, BS2, . . . , are distributed in aservice area covered by the mobile communication system. The basestations BS1, BS2, . . . , form radio communication areas E1, E2, . . ., respectively, which are called cells. A mobile communication terminalMS serving as a mobile station is connected to the nearest base stationvia a radio channel.

The base stations BS1, BS2, . . . , are classified into a first basestation group using a first communication mode, and a second basestation group using a second communication mode that includes anupgraded part of the standard of the first communication mode. Forexample, the first base station group uses IS95A or IS95B which is aCDMA standard, and the second base station group uses IS2000-1X that isformed by adding a high-speed data transmission mode to the IS95A orIS95B standard.

The mobile communication terminal MS has functions corresponding to bothcommunication modes of IS95A or IS95B and IS2000-1X. In addition, themobile communication terminal MS has functions corresponding to apersonal mobile communication system using CDMA, which is represented byPCS (Personal Communication System), and to an analog mobile phonesystem using an analog communication mode, which is represented by AMPS(Advanced Mobile Phone System).

FIG. 2 is a block diagram showing the functional structures of themobile communication terminal MS.

In FIG. 2, a radio signal sent from the base station BS1, BS2, . . . ,is received by an antenna 1 and input to a reception circuit (RX) 3 viaa duplexer (DUP) 2. In the reception circuit 3, the radio signal ismixed with a reception local oscillation signal produced from afrequency synthesizer (SYN) 4 and is down-converted to an intermediatefrequency signal or a baseband signal. The frequency of the receptionlocal oscillation signal produced from the frequency synthesizer 4 isinstructed by a control signal SYC from a control section 12.

The reception intermediate-frequency signal or reception baseband signalis input to a CDMA signal processing section 6 when the communicationmode is set to be a digital mode using CDMA, or to an analog audiocircuit 19 when the communication mode is set to be an analog mode.

The CDMA signal processing section 6 subjects the input receptionintermediate frequency signal or reception baseband signal to aquadrature demodulation process and a despread spectrum process using aspread code assigned to a reception channel. Thereby, demodulated datacorresponding to a data rate is obtained. The demodulated data is inputto a speech codec 7. Control data indicative of a data rate, which isincluded in the demodulated data, is input to the control section 12.

The speech codec 7 subjects the demodulation data output from the CDMAsignal processing section 6 to an expansion process corresponding to thereception data rate informed from the control section 12. In addition,the speech codec 7 subjects the expanded data to a decoding processusing Viterbi decoding, etc. and an error correction decoding process,thereby reproducing baseband reception digital data.

A PCM codec 8 performs different signal processing according to acommunication type (voice communication or data communication) informedfrom the control section 12. Specifically, in the voice communicationmode, the PCM codec 8 performs PCM decoding of the reception digitaldata output from the speech codec 7 and produces an analog receptioncall signal. The analog reception call signal is amplified by areception call amplifier 9 and output from a loudspeaker 10. On theother hand, in the data communication mode, the reception digital datafrom the speech codec 7 is fed to the control section 12. The controlsection 12 stores the reception digital data in a storage section 13 andcauses it to be displayed on a display section 15.

The reception digital data, where necessary, may be transferred to anexternal information terminal device (not shown) such as a personaldigital assistant (PDA) or a notebook personal computer via an externalinterface (not shown).

On the other hand, the analog audio circuit 19 analog-demodulates theinput reception intermediate frequency signal through an FM detector andreproduces an analog reception call signal. The analog reception callsignal is amplified by the reception call amplifier 9 and output fromthe loudspeaker 10.

An input voice of the speaker in the voice communication mode is inputthrough a microphone 11 as an analog transmission call signal. Theanalog transmission call signal is amplified up to a proper level by atransmission call amplifier 18. When the digital mode is set as thecommunication mode, the amplified signal is input to the PCM codec 8.When the analog mode is set as the communication mode, the amplifiedsignal is input to the analog audio circuit 19.

The PCM codec 8 subjects the input analog transmission call signal to aPCM encoding process. The transmission data thus produced is supplied tothe speech codec 7. In addition, data produced from the externalinformation terminal device is input to the control section 12 via theexternal interface (not shown). The data is then delivered from thecontrol section 12 to the speech codec 7 via the PCM codec 8.

In the voice communication mode, the speech codec 7 detects an energyamount of the input voice on the basis of transmission voice dataproduced from the PCM codec 8. Based on the detection result, the speechcodec 7 determines the data rate. The speech codec 7 compresses thetransmission data to a burst signal of a format corresponding to thedata rate, and subjects it to an error correction encoding process. Thespeech codec 7 delivers the resultant data to the CDMA signal processingsection 6. On the other hand, in the data communication mode, the speechcodec 7 compresses the transmission data from the PCM codec 8 to a burstsignal of a format corresponding to a preset data rate and subjects itto an error correction encoding process. The speed codec 7 delivers theresultant data to the CDMA signal processing section 6. The data rate ineither the voice communication mode or data communication mode isinformed to the control section 12 as a transmission data rate.

The CDMA signal processing section 6 subjects the burst signalcompressed by the speech codec 7 to a spread process using a spread codeassigned to the transmission channel. Then, the CDMA signal processingsection 6 subjects the spread-coded transmission signal to a quadraturemodulation process and delivers the quadrature-modulated signal to atransmission circuit (TX) 5.

On the other hand, the analog audio circuit 19 modulates a carriersignal by the input analog transmission call signal, using an analogmodulation method such as an FM modulation method. The analog audiocircuit 19 outputs the modulated carrier signal to the transmissioncircuit (TX) 5.

The transmission circuit 5 mixes the input quadrature-modulated signalor carrier signal with a transmission local oscillation signal producedfrom the frequency synthesizer 4, and converts the resultant signal to aradio frequency signal. Based on the transmission data rate informedfrom the control section 12, the transmission circuit 5 subjects only aneffective component of the radio frequency signal to radio frequencyamplification and outputs the RF amplified signal as a transmissionradio frequency signal. The transmission radio frequency signal producedfrom the transmission circuit 5 is fed to the antenna 1 via the duplexer2. The transmission radio frequency signal is then burst-transmitted tothe base station (not shown) from the antenna 1.

An input section 14 is provided with keys including a dial key, a sendkey, a power key, an end key, a volume control key, and a modedesignating key. The display section 15 is provided with an LCD displayand an LED. The LCD display displays, for example, information in aphone book, an incoming call and an outgoing call history, a telephonenumber of a counter-part terminal, and an operation state of thisterminal. The LED is turned on or flickered when an incoming call hasbeen received or when a discharge state of a battery 16 is indicated,that is, information demanding recharging of the battery 16 isdisplayed.

Reference numeral 17 denotes a power supply circuit. Based on an outputfrom the battery 16, the power supply circuit 17 produces apredetermined power supply voltage Vcc and supplies it to each circuitcomponent. The power supply circuit 17 includes a recharging circuit forrecharging the battery 16.

The control section 12 includes, for example, a microcomputer as a maincontrol unit. In addition to conventional control functions such as aradio communication control function and a position register controlfunction, the control section 12 has a base station acquisition controlfunction 12 a and a communication mode display control function 12 b ascontrol functions relating to the present invention. The radiocommunication control function executes a radio channel connectioncontrol in accordance with a incoming call and outgoing call, thusenabling voice communication or data communication.

The base station acquisition control function 12 a executes a search forthe base station BS1, BS2, . . . , when power is turned on, when a idlehandoff is effected in a standby state, when a handoff is effectedduring information communication, or when selection or re-selection ofthe system is effected. Based on the search result, the base stationthat meets the condition for communication is selected, and a processfor acquiring the selected base station is performed.

In the communication mode display control function 12 b, a controlmessage is received from the base station acquired by the base stationacquisition control function 12 a, and data indicative of thecommunication mode is extracted from the received control message. Basedon the extracted data, display data for notifying the user of thecommunication mode is produced and the produced display data isdisplayed on the LCD display of the display section 15. A markrepresentative of the communication mode, for instance, is used as thedisplay data.

The base station acquisition control function 12 a and communicationmode display control function 12 b are realized by causing themicroprocessor of control section 12 to execute programs. The programsare stored in a program memory in the control section 12 or in a programstorage area in the storage section 13.

There are three methods of storing the programs in the program memory orthe program storage area: 1) to record programs by means of a programwriter at the time of manufacture or assembly, 2) to read programs froman external memory such as a CD-ROM or a memory card at the time ofstarting the operation of the terminal and to write the read programs inthe program memory or the program storage area, and 3) to downloadprograms from the Web site of a communication service provider or amanufacturer via a communication network, and to write the downloadedprograms in the program memory or program storage area.

The operation of the mobile communication terminal MS with the abovestructure will now be described.

When power has been turned on or when a handoff is effected in thestandby state, the mobile communication terminal MS performs thefollowing communication mode display operation. FIG. 3 shows a sequenceillustrating the control procedures and control contents.

When power has been turned on, the control section 12 of the mobilecommunication terminal MS executes a base station search process in step3 a. In the base station search process, the terminal MS successivelyreceives pilot signals transmitted from neighboring base stations andmeasures the quality of reception of the pilot signals. Based on ameasured result of the quality of reception, the best base station to beacquired is selected.

Assume that the mobile communication terminal MS is located at a boarderarea between the radio area E2 and radio area E5, as shown in FIG. 1.Assume also that the quality of reception of the pilot signal from thebase station BS2 is higher than that of the pilot signal from the basestation B5. In this case, the control section 12 of the mobilecommunication terminal MS receives a sync channel signal sent from theselected base station BS2 and performs a process for establishing syncwith the base station BS2 on the basis of the sync channel signal (step3 b). If sync is established, the reception channel is switched to thepaging channel, and the control section 12 is set in the standby state(step 3 d). At this time, the control section 12 executes a process fordisplaying information representing the communication mode in step 3 c.

To be more specific, the control section 12 receives an extended systemparameters message (ESPM) sent from the base station BS2 over the pagingchannel. FIG. 4 shows a format of the ESPM. Data indicative of thecommunication mode used by the base station BS2 is extracted from aP_REV field P1 of the received ESPM. Based on the extracted data, adisplay mark of the communication mode is generated. The generateddisplay mark is displayed on a PICT information display area 15 a of theLCD display provided in the display section 15.

If the communication mode of the base station BS2 is IS2000-1X, datarepresentative of IS2000-1X is put in the P REV field P1 of the incomingESPM from the base station BS2. Thus, the PICT information display area15 a of LCD display displays mark “1X” indicative of the IS2000-1X. InFIG. 7, numeral 4 a denotes an example of display.

The user can confirm the communication mode of the base station BS2acquired by the terminal, on the basis of the mark 4 a displayed on thePICT information display area 15 a.

The control section 12 in the standby state 3 d periodically performs abase station search in step 3 e. Based on the quality of reception ofthe pilot signal from the neighboring base stations, which is measuredby the base station search, the control section 12 determines in step 3f whether an idle handoff is necessary or not.

Assume that the mobile communication terminal MS has moved closer to thebase station BS5, as indicated by MS′ in FIG. 1. In this case, thequality of reception of the pilot signal from the base station BS5becomes higher than that of the pilot signal from the base station BS2.The control section 12 thus determines that a handoff is necessary andadvances to step 3 g. In step 3 g, the control section 12 receives async channel signal sent from the base station BS5 and executes anoperation for establishing sync with the base station BS5 on the basisof the sync channel signal. If sync is established, the receptionchannel is switched to the paging channel, and the control section 12 isset in the standby state 3 i. At this time, the control section 12executes a communication mode display changing process in step 3 h.

To be more specific, the control section 12 receives an ESPM sent fromthe base station BS5 (i.e. a handoff destination) over the pagingchannel, and extracts data representative of the communication mode usedby the base station BS5 (the handoff destination) from the P_REV fieldP1 of the received ESPM. Based on the extracted data, a display mark ofthe communication mode is generated. The generated display mark isdisplayed on the PICT information display area 15 a of the LCD display.

If the communication mode of the base station BS5 of the handoffdestination is IS95A or 95B, data representative of IS95A or 95B is putin the P_REV field P1 of the incoming ESPM from the base station BS5.Thus, the PICT information display area 15 a of LCD display displaysmark “D” indicative of the IS95A or 95B. In FIG. 8, numeral 4 b denotesan example of display.

The display of “1X” indicative of the communication mode of the basestation BS2 (i.e. a handoff origin) is kept until the communication mode“D” of the base station BS5 of the handoff destination is displayed. Inshort, the communication mode of the base station BS2 of the handofforigin is displayed during the idle handoff process.

The user can thus confirm the communication mode of the base station BS5acquired by the mobile communication terminal MS′ even after the idlehandoff. Therefore, the user can confirm the communication mode andperforms the information communication of the format suitable for theusable communication mode.

For example, when large-volume data communication is to be performed asin a case of downloading image content or music content from a Web pageor a Web site, this data communication can be performed when the IS2000-1X standard with the high-speed data transmission mode is usable.

A communication mode display control in the case where a handoff iseffected during the information communication will now be described.FIG. 5 shows a sequence illustrating the control procedures and controlcontents.

Assume that the mobile communication terminal MS is performing radiocommunication with the base station BS2 according to the IS2000-1Xstandard. At this time, the PICT information display area 15 a of theLCD display displays the mark “1X” indicating that the communicationmode in use is IS2000-1X.

In this communication state 5 a, the control section 12 periodicallyperforms a base station search in step 5 b. Based on the quality ofreception of the pilot signal from the neighboring base stations, whichis measured by the base station search 5 b, the control section 12determines in step 5 c whether an idle handoff is necessary or not.

Assume that the mobile communication terminal MS has moved closer to thebase station BS5, as indicated by MS′ in FIG. 1. In this case, thequality of reception of the pilot signal from the base station BS5becomes higher than that of the pilot signal from the base station BS2.The control section 12 thus determines that a handoff is necessary andexecutes the following handoff process.

To start with, the control section 12 prepares a message (PSMM: PilotStrength Measurement Message) representative of the quality of receptionof the pilot signal from each of the neighboring base stations, whichhas been measured by the base station search 5 b, and sends the PSMM tothe base station BS2 which is currently acquired. Upon receiving thePSMM, the base station BS2 returns an acknowledge message (BSACK) forthe PSMM to the mobile communication terminal MS. Then, the base stationBS2 prepares a message indicative of the handoff destination (EHDM(Extended Handoff Direction Message) or GHDM (General Handoff DirectionMessage) and sends the EHDM or GHDM to the mobile communication terminalMS requesting the handoff.

Upon receiving the EHDM or GHDM, the control section 12 of the mobilecommunication terminal MS executes a process for establishing sync withthe base station BS5 of the handoff destination according to the EHDM orGHDM, while maintaining the radio link with the base station BS2 that iscurrently acquired. If sync is established and a radio link isestablished by the traffic channel, the control section 12 prepares ahandoff-completion message (HOCM: Handoff Completion Message) and sendsit to the base station BS2 of the handoff origin. Thus, the mobilecommunication terminal MS passes into a state 5 d in which the terminalMS is connected to both the base station BS2 of the handoff origin andthe base station BS5 of the handoff destination.

In this state, the control section 12 of mobile communication terminalMS monitors the quality of reception of the pilot signals from the basestation BS2 of the handoff origin and the base station BS5 of thehandoff destination. If a difference in quality between both pilotsignals exceeds a threshold, the control section 12 sends a PSMM to eachof the base stations BS2 and BS5. Upon receiving the PSMM, each of thebase stations BS2 and BS5 returns an acknowledge message BSACK to themobile communication terminal MS of the handoff request origin. Inaddition, each of the base stations BS2 and BS5 prepares an EHDM or GHDMand sends it to the mobile communication terminal MS. FIG. 6 shows aformat of the EHDM.

Upon receiving the EHDM or GHDM from each of the base stations BS2 andBS5, the control section 12 of the mobile communication terminal MSreleases the radio link with the base station BS2 of the handoff originaccording to the instruction of the EHDM or GHDM. If this radio linkrelease process is completed, the mobile communication terminal MSprepares an HOCM and sends it to each of the base station BS2 of thehandoff origin and the base station BS5 of the handoff destination.Thus, the mobile communication terminal MS passes into a state 5 g inwhich it is connected to only the base station BS5 of the handoffdestination.

In step 5 e of the handoff process, the control section 12 of mobilecommunication terminal MS extracts data representative of thecommunication mode used by the base station BS5 of the handoffdestination from the P_REV field P2 of the EHDM or GHDM sent from thebase station BS5 of the handoff destination. In step 5 f, uponconfirming the reception of an acknowledge message BSACK from the basestation BS5 of the handoff destination in response to the HOCM, thecontrol section 12 generates a display mark of the communication modebased on the data extracted from the P REV field P2, and displays it onthe PICT information display area 15 a of the LCD display.

For example, if the communication mode of the base station BS5 of thehandoff destination is IS95A or 95B, the PICT information display area15 a of the LCD display displays mark “D” indicative of the IS95A or 95Bstandard, as shown in FIG. 8 by numeral 6 b.

In the above handoff process, the display of “1X” indicative of thecommunication mode of the base station BS2 of the handoff origin is keptuntil the reception of the HDM from the base station BS5 of the handoffdestination and the completion of the handoff process. In short, in thehandoff process in the information communication, too, the communicationmode of the base station BS2 of the handoff origin is displayed untilthe completion of the series of handoff process procedures.

Accordingly, even when the handoff is effected during the informationcommunication and consequently the communication mode has changed, theuse can also recognize the change of the communication mode. Forexample, when the communication mode has been changed from IS2000-1X toIS95A or 95B during large-volume data communication, the user can returnto the radio communication area E2 of base station BS2 or finish thedata communication in an incomplete state.

As has been described above, according to the present embodiment, thedata representative of the communication mode is extracted from theP_REV field P1, P2 of the ESPM, EHDM or GHDM coming from the newlyacquired base station, when the power is turned on, when the idlehandoff is performed in the standby state, or when the handoff iseffected in the information communication. Based on the extracted data,the display mark indicative of the communication mode used by theacquired base station is generated, and the generated mark is displayedon the PICT information display area 15 a of the LCD display.

Accordingly, the user can always confirm the communication mode of thebase station acquired by his/her mobile communication terminal MS, whenthe idle handoff is effected in the standby state, or when the handoffis effected during the information communication, as well as when thepower is turned on. Therefore, the user can confirm the displayedcommunication mode and select the information communication of theformat suitable for the usable communication mode.

The present invention is not limited to the above-described embodiment.For example, in the above embodiment, a handoff is performed between aplurality of base stations belonging to one mobile communication system.However, the communication mode display control of the present inventioncan be applied to the case where a so-called system selection isperformed to switch the system of connection destination among aplurality of mobile communication systems. In this case, too, anincoming system parameter message is received from a base station of asystem which has been newly selected by the system selection process.Data representative of the communication mode is extracted from thereceived message, and informed to the user. In this fashion, thecommunication mode display control can similarly be realized.

In the above-described embodiment, when power has been turned on, datarepresentative of the communication mode is extracted from the P_REVfield set in the ESPM sent from the acquired base station over thepaging channel, and the extracted data is displayed. Alternatively, datarepresentative of the communication mode may be extracted from the P_REVfield set in the sync channel message sent from the acquired basestation, and the extracted data is displayed.

In the above embodiment, a soft handoff has been described as a handoffoperation during information communication. However, this invention isalso applicable to a hard handoff including radio frequency changes.

When the communication mode has been changed by the handoff process, thedisplay mark “1X” or “D” indicating the changed communication mode maybe flickered, or a display message indicating the change of thecommunication mode may additionally be generated and displayed.Moreover, the change of the communication mode may be reported to theuser by alerting sound or vibration. Thereby, the user can clearlyrecognize the change of the communication mode.

The communication mode indication means is not limited to the displayingof the mark representative of the communication mode. A display messageindicating the communication mode may be generated and displayed. Inaddition, a voice message indicating the communication mode may begenerated using speech synthesis technology and output from aloudspeaker.

In the above embodiment, the mobile communication system wherein a basestation using IS95A/95B and a base station using IS2000-1X are mixedlypresent has been described by way of example. The invention is alsoapplicable to systems wherein base stations using other communicationmodes are mixedly present.

Means for designating and inputting a communication mode desired by theuser may be provided. It is determined whether the communication mode ofthe acquired base station agrees with the desired communication modedesignated by the user. If the communication modes do not coincide, amessage to this effect, together with information representative of thecommunication mode, is informed to the user. Thereby, if a base stationusing the communication mode desired by the user has not been acquired,the user can clearly recognize this fact. The possibility ofcommunication being performed with an undesired communication mode canfurther be reduced.

A function of accepting a base station re-acquisition request and a basestation re-acquisition control function may further be provided. Assumethat the user, who was notified of the communication mode, has input are-acquisition request for changing the already acquired base station toa base station using the desired communication mode. In this case, asearch for neighboring base stations is conducted once again accordingto the request. Based on the search result, it is determined whetherthere is a base station using the communication mode desired by theuser. If there is an acquirable base station among base stations usingthe communication mode desired by the user, a process is executed tochange the acquired base station to this one. If there is no acquirablebase station among base stations using the communication mode desired bythe user, a message indicating the impossibility of change of the basestation and the reason therefor is generated and informed to the userwhile the already acquired base station is maintained.

With this structure, when a base station using the desired communicationmode is not acquired, the user can make the terminal executere-acquisition of the base station by a simple operation. In addition,when a base station using the desired communication mode cannot beacquired, the user can clearly recognize this fact and the reason.Accordingly, the user can clearly know the reason why the desiredcommunication mode cannot be used, and the user can take an appropriatemeasure, for example, by moving into a radio area of some other basestation.

In the above embodiment, in the idle handoff effected in the standbystate, the communication mode is displayed on the basis of the pagingsignal first sent from the base station with which the terminal has beensynchronized. Then, the terminal is set in the standby state.Alternatively, after the terminal passes in the standby state, pagingsignals that are periodically sent from base stations may be received todetect the P-REV value. The just detected value and the previouslyreceived value are compared, and the display of the communication modemay be updated if there is change or addition.

The kinds of communication modes, the kinds and structures of the mobilecommunication terminal, the communication mode indication controlprocedure and the contents thereof, the content of indicationinformation (e.g. including information representative of a changed oradded function), the kinds and structure of indication means, etc., maybe modified without departing from the spirit of the present invention.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. A mobile communication terminal connectable to a base stationcomprising: means for acquiring a base station; means for receiving acontrol message sent from the base station acquired by the acquiringmeans; means for recognizing whether the communication mode in use atthe acquired base station is one of a first communication mode and asecond communication mode based on the received control message, whereinthe second communication mode is upgraded from the first communicationmode; and means for indicating the recognized communication mode.
 2. Theterminal according to claim 1, wherein the acquiring means acquires thebase station when the mobile communication terminal is turned on; andthe recognizing means recognizes the communication mode in use at thebase station.
 3. The terminal according to claim 1, wherein the acquiredbase station is adapted to use both the first communication mode and thesecond communication mode.
 4. In a mobile communication networkincluding base stations configured to operate according to a firstcommunication standard and base stations configured to operate accordingto a second communication standard different from the firstcommunication standard, a mobile communication terminal configured to beconnected to a base station, the mobile communication terminalcomprising: means for acquiring a base station; means for receiving acontrol message sent from the acquired base station; means forrecognizing whether the acquired base station is assigned to operatewith the mobile communication terminal according to the firstcommunication standard or the second communication standard based on thereceived control message; and means for indicating the recognizedcommunication standard by which the acquired base station is configuredto operate with the mobile communication terminal.
 5. The mobilecommunication terminal according to claim 4, wherein the secondcommunication standard is upgraded from the first communicationstandard.
 6. The mobile communication terminal according to claim 4,wherein the acquired base station is configured to operate according toboth the first communication standard and the second communicationstandard.
 7. The mobile communication terminal according to claim 4,wherein the acquiring means acquires the base station responsive to themobile communication terminal being turned on.